Enjoy Pilot's popular FriXion ink in a lean pen body. And a lean tip size! The FriXion Ball Slim has a 0.38 mm tip, perfect for everyday writing as well as the tiny annotations you need to cram into the margins of your textbooks. The svelte clip-less profile lets you pile a bunch of them in your pen case with room to spare for more pens and pencils. You can even hang your pen, by stringing a lanyard through the hole in the knocker. FriXion ink is a thermosensitive ink that can be erased by rubbing. To erase, use the special rubber “eraser” tip at the top of the pen and watch the ink cleanly disappear. Interestingly, erased ink reappears at temperatures below 14° F (-10° C). A freezer is cold enough to make this happen. It is like magic ink for adults! Due to the thermosensitive nature of FriXion ink, we advise against using it for mailings, or leaving the written materials in hot cars or in environments that expose them to a lot of friction. Note: To change the refill, unscrew the transparent grip area to remove it. Pull out the old refill and insert the new refill, ensuring that it is securely held in place. Then, screw the transparent piece back on.